The present invention is directed to novel organometallic luminescent materials, and, more particularly, to a novel organometallic luminescent material having the capability of emitting a wide range of colors including blue and green light, and high thermal stability, and an organic luminescent device containing same.
Conventional organometallic luminescent compounds used in organic electroluminescent devices are mostly complexes of di- or trivalent metals such as zinc and aluminium.
For example, U.S. Pat. No. 5,456,988 describes 8-hydroxyquinoline complexes of zinc, aluminium and magnesium as organic luminescent materials; U.S. Pat. No. 5,837,390 discloses magnesium, zinc and cadmium complexes of 2-(o-hydroxyphenylbenzoxazole); Japanese Patent Laid-Open Publication No. 07-133483 reports luminescent complexes of 2-(o-hydroxyphenylbenzoxazole) with divalent metals such as magnesium and copper; and U.S. Pat. No. 5,529,853, and Japanese Patent Laid-Open Publication Nos. 06-322362, 08-143548 and 10-072580 disclose divalent or trivalent metal complexes of 10-hydroxybenzo[10]quinoline.
The above organometallic luminescent compounds containing a divalent or trivalent metal have relatively loosely bound ligands and an extended system of conjugation. As a result, they are relatively unstable and emit green or red light but not a blue light.
Therefore, there has existed a need to develop an organometallic luminescent material having improved stability and light emission characteristics such as the capability of emitting a blue light.
Accordingly, it is a primary object of the present invention to provide a novel organometallic luminescent material having the stability and desired emission characteristics, and an organic luminescent device containing same.
In accordance with the present invention, there is provided an organometallic luminescent material selected from the group consisting of the compounds of formulae (I) to (V). 
wherein,
M1 and M4 are each independently a monovalent or tetravalent metal selected from the group consisting of Li, Na, K, Zr, Si, Ti, Sn, Cs, Fr, Rb, Hf, Pr, Pa, Ge, Pb, Tm and Md;
M2 is a mono-, di-, tri- or tetravalent metal selected from the group consisting of Li, Na, K, Ca, Be, Ga, Zn, Cd, Al, Cs, Fr, Rb, Mg, Mn, Ti, Cu, Zr, Si, Hf, Pr, Pa, Ge, Sn, Pb, Tm and Md;
M3 is selected from the group consisting of Li+, Na+, K+, Cs+, Fr+, Rb+, Ca2+, Be2+, Ga3+, Zn2+, Al3+, Mg2+, Mn2+, Ti2+ and Cu2+;
R is a hydrogen or C1-10 alkyl;
X and Y, which can be the same or different, are independently a hydrogen, Cl, F, I, Br or SO3H;
A is a hydrogen, F, Cl, Br or I;
B is O, S, Se or Te;
D is O or S; and
n is an integer ranging from 1 to 4.